Java enum format

play-json/shared/src/main/scala/play/api/libs/json/JavaEnumFormat.scala

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package play.api.libs.json
+
+/**
+ * Helper for format a java enum into or from json
+ *
+ * public enum TestEnum {
+ *
+ *   TEST1,
+ *   TEST2,
+ *   OKAY
+ *
+ * }
+ *
+ * implicit val  TestEnumFormat = JavaEnumFormat.format[TestEnum]
+ *
+ */
+object JavaEnumFormat {
+  def format[A <: Enum[A]](implicit m: scala.reflect.Manifest[A]): Format[A] = {
+    new JsonJavaEnumFormat[A]
+  }
+}
+
+/**
+ * Format for java enums from and to json
+ *
+ * @tparam A the type of the enum
+ */
+class JsonJavaEnumFormat[A <: Enum[A]](implicit m: scala.reflect.Manifest[A]) extends Format[A] {
+  def reads(json: JsValue) = JsSuccess(Enum.valueOf[A](m.runtimeClass.asInstanceOf[Class[A]], json.as[String]))
+
+  def writes(enumValue: A) = JsString(enumValue.name())
+}

play-json/shared/src/test/scala/play/api/libs/json/JavaTestEnum.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package play.api.libs.json;
+
+
+public enum JavaTestEnum {
+
+  TEST_1(true),
+
+  TEST_2(false);
+
+  public final boolean testPriv;
+
+  JavaTestEnum(boolean testPriv) {
+    this.testPriv = testPriv;
+  }
+}

play-json/shared/src/test/scala/play/api/libs/json/JavaTestsEnumsFormat.scala

@@ -0,0 +1,10 @@
+/*
+ * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package play.api.libs.json
+
+object JavaTestsEnumsFormat {
+  implicit val testsEnumsFormat = JavaEnumFormat.format[JavaTestEnum]
+}
+

play-json/shared/src/test/scala/play/api/libs/json/ReadsSharedSpec.scala

@@ -158,6 +158,14 @@ class ReadsSharedSpec extends WordSpec with MustMatchers {
     }
   }
 
+  "JavaEnumFormat" should {
+    import JavaTestsEnumsFormat._
+    "deserialize correctly java enum with names" in {
+      JsString("TEST_1").validate[JavaTestEnum] mustEqual JsSuccess(JavaTestEnum.TEST_1)
+      JsString("TEST_2").validate[JavaTestEnum] mustEqual JsSuccess(JavaTestEnum.TEST_2)
+    }
+  }
+
   // ---
 
   case class Owner(

play-json/shared/src/test/scala/play/api/libs/json/WritesSharedSpec.scala

@@ -76,6 +76,14 @@ class WritesSharedSpec extends WordSpec with MustMatchers {
     }
   }
 
+  "JavaEnumFormat" should {
+    import JavaTestsEnumsFormat._
+    "serialize correctly java enum with names" in {
+      Json.toJson(JavaTestEnum.TEST_1) mustEqual JsString("TEST_1")
+      Json.toJson(JavaTestEnum.TEST_2) mustEqual JsString("TEST_2")
+    }
+  }
+
   // ---
 
   case class Location(lat: Double, long: Double)